Parasitoid wasps that utilize the hemocoel of another insect to harbor their developing young have evolved mechanisms to protect their eggs against host cellular defense systems. Leptopilina heterotoma suppresses an immune response in its host Drosophila melanogaster by destroying the host's blood cells that encapsulate and reject foreign objects. In the absence of these cells, the lamellocytes, the parasitoid eggs develop undisturbed in a host environment that would otherwise be hostile. The female wasp creates this immune deficiency by injecting a substance from an accessory gland along with its egg into the host hemocoel. This substance has been named lamellolysin since it selectively destroys lamellocytes while allowing the other types of host blood cells to function normally. The project will examine this parasitoid-host relationship to understand how lamellolysin targets a specific type of blood cell for destruction. The study will involve isolation of lamellolysin and charcterization of its physical and chemical properties. An antibody directed against lamellolysin will be prepared and used to study the binding of lamellolysin to the blood cells of parasitized Drosophila larvae. Hopefully, the latter examination will provide information on the apparent specificity of lamellolysin for lamellocytes. After information on the molecular properties of lamellolysin and its cellular target in Drosophila are available, the effects of lamellolysin on cells of the vertebrate cellular immunity system will be examined to determine whether this factor(s) has any applications as an immune suppressant in vertebrates.